Synthesis and crystal structures of a series of complexes based on a rigid angular ligand and the magnetic properties of the Cu(ii) polymer

Abstract

Treatment of 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (bpodz) with AgNO3, Cu(OAc)2, CoSO4, CdI2 or MnSO4 afforded five complexes, the coordination polymers [Ag(bpodz)(μ-NO3)]n (1), {[Cu2(bpodz)(μ-OAc)4](CH3OH)2}n (2), {[Co(bpodz)(SO4)(H2O)3](CH3OH)2}n (3) and [Cd(bpodz)2(μ-I)2]n (4), and the complex [Mn(bpodz)2(SCN)2(H2O)2] (5). These compounds have been structurally characterized by X-ray single crystal diffraction. 1 is a 2-D network polymer constructed by ladder-like chains. In these chains, the nitrate anions are shared by two silver(I) to form a rhombic Ag2O2 plane. Polymer 2 is a 1-D wave-like chain in which the copper(II) atoms bridged by the acetate groups are separated by a distance of 2.623 A. Polymer 3 shows a 1-D linear structure, in which interchain H-bonding interactions contribute to the final 2-D networks. Polymer 4 crystallizes as infinite CdI2 chains in which cadmium(II) ions are doubly bridged by pairs of iodine atoms; the bpodz complete the octahedral coordination of the cadmium atoms, but act as monodentate ligands so do not to link the CdI2 chains to form extended 2-D layers. Complex 5 is constructed into a 2-D stair-like structure through hydrogen bonds. Magnetic susceptibility data for polymer 2, measured from 5 to 300 K, show strong antiferromagnetic coupling. These data were fitted to the appropriate equations derived from the Hamiltonian H = −2JS1S2, giving the parameter −2J = 320 cm−1.